1. Field of the Invention
The present invention relates to golf balls. More particularly, the present invention relates to solid golf balls having a core, a mid layer and a cover.
2. Description of the Related Art
Golf balls used for playing golf at a golf course are generally classified into: wound golf balls having a core comprising wound rubber threads; and solid golf balls having a core comprising a solid rubber. Wound golf balls have been conventionally used, with a period during which the wound golf balls account for almost all of the first-class golf balls. However, solid golf balls that have been developed afterwards can be readily manufactured at a lower cost, therefore, larger number of solid golf balls have been recently supplied to the market than the wound golf balls. In general, solid golf balls have drawbacks in a feel at impact being hard compared to wound golf balls. To the contrary, common solid golf balls are more excellent in terms of a travel distance than wound golf balls. In an attempt to improve a feel at impact and to further enhance a flight performance, solid golf balls having a mid layer between a core and a cover have been proposed and placed on the market.
Meanwhile, a variety of techniques have been proposed where particles (solids) comprising a crosslinked rubber or a synthetic resin are blended in a core of a solid golf ball. For example, a core blended with particles of ebonite that is a highly hard rubber is disclosed in Japanese Patent Publication Reference JP-A-94666/1986. In Japanese Patent Publication Reference JP-A-91019/1994, there is disclosed a core blended with high molecular weight polyethylene (trade name: “Miperon XM220”) having Shore D hardness of about 65. In Japanese Patent Publication Reference JP-A-185039/1995, there is disclosed a golf ball with mitigated impulsive force at impact through blending vulcanized rubber powder having a particle diameter of from 0.8 mm to 7.0 mm in a core. In Japanese Patent Publication Reference JP-A-314342/1998, there is disclosed a golf ball having a central core layer, an outer core layer, an inner cover layer (This inner cover layer can be also assumed as an outermost layer of the core.) and an outer cover layer, wherein polypropylene powder is blended in the core.
In Japanese Patent Publication Reference JP-A-583/2001, there is disclosed a golf ball having a core blended with particles of which hardness being higher than the hardness of the core surface. In Japanese Patent Publication Reference JP-A-584/2001, there is disclosed a golf ball having a core blended with particles of which difference from the core being small in their specific gravity. In Japanese Patent Publication Reference JP-A-587/2001, there is disclosed a golf ball having a core blended with particles, without exposure of these particles to the core surface. Japanese Patent Publication Reference JP-A-29511/2001 discloses a golf ball having a mid layer including rubber particles dispersed in a thermoplastic resin.
Even with these golf balls including particles blended therein, concomitant achievement of favorable flight performance and soft feel at impact has not been enabled. The present invention was made taking into account of such circumstances, and an object of the present invention is to provide golf balls which are excellent in both respects of the flight performance and feel at impact.